The present invention relates to integrated circuit (IC) chip reliability and, more particularly, to a method for performing reliability qualification of manufactured integrated circuit (IC) chips using a process window-aware sample-specific expected fail rate, which accounts for the fact that failure mechanisms that impact IC chip reliability may be process window-dependent.
Various failure mechanisms can cause the components (e.g., devices, interconnects, etc.) of an integrated circuit (IC) chip to degrade. These failure mechanisms include, but are not limited to, time-dependent dielectric breakdown (TDDB) of the gate dielectric layer or between metal lines, hot carrier injection (HCI), negative bias temperature instability (NBTI), positive bias temperature instability (PBTI), soft error rate (SER), retention disturbance, stress migration (SM) (also referred to as stress-induced voiding (SIV)) and electromigration (EM). Over time these failure mechanisms can impact performance (e.g., operating speed) and/or lead to IC chip failure.
In order to ensure that manufactured IC chips will meet reliability specifications despite these failure mechanisms, reliability qualification is performed prior to shipping out the manufactured IC chips and/or incorporating them into products. Specifically, during reliability qualification, a sample of the manufactured IC chips is stress tested to determine whether the sample meets reliability specifications and, particularly, whether the sample has a fail rate that is no greater than an expected overall fail rate for all of the manufactured IC chips. If the actual fail rate for the sample is less than or equal to the expected overall fail rate, the manufactured IC chips can be shipped and/or incorporated into products. However, if the actual fail rate for the sample is higher than the expected overall fail rate for the manufactured IC chips, the manufactured IC chips may have to be scrapped or recycled (i.e., not shipped or incorporated into products, as planned) and instead design changes and/or process changes may need to be developed. Errors during reliability qualification can lead to unreliable IC chips being shipped and/or incorporated into products and reliable IC chips being scrapped or recycled. Thus, accurate techniques for performing reliability qualification are needed.